The mechanical response of a small volume of material near the surface of a sample is studied by probing the surface with a diamond indenter of known geometry.  A piezoelectric transducer drives the indenter into the sample surface while load, depth of penetration, and displacement data are continuously collected.

Equipment:

The micromechanical tester was designed and built at IBM San Jose. Diamond indenters:

• Vickers (square pyramid)
• Knoop (elongated square pyramid)
• Berkovich (triangular pyramid)
• right circular cones with tip radii of 1, 5, 10, and 50 µm

Semi-automated PC interface to control the machine and collect data.

Accessories:

• Hot stage: fixed temperatures from ambient to 100 °C
• Tangential load cell for measuring lateral forces

Applications:

The instrument may be used to characterize the mechanical properties and adhesion strength of films.  Indentation, microscratch, load relaxation, indentation fatigue, indentation creep, and dynamic mechanical experiments can be performed on coatings to obtain information on hardness, elastic modulus, storage and loss moduli, friction coefficients, film adhesion, and fracture toughness.  3 and 4 point bending, tensile, compression, crush, peel and fiber pushout tests can also be performed.

Scratch tests are performed by drawing the indenter across the surface as it penetrates.  Delamination of films allows qualitative and, in some cases, quantitative evaluation of interfacial properties.

Virtually any test that requires pushing or pulling under carefully controlled conditions within the physical limits of the equipment can be performed.

Materials and coatings of all kinds from highly viscous polymers to diamond-like carbon have been studied.

Capabilities:

• Maximum Sample size: Specimens 2 cm high and 5 cm across.  Larger samples can be accommodated with some geometrical constraints.  A smooth surface produces best results.
• Load resolution: 50 µN
• Depth resolution: 5 nm